considerations on the adult morphology of the west ... · , in the latter the occipital carina...

of 16 /16
Lucrările Simpozionului „Entomofagii şi rolul lor în păstrarea echilibrului naturalUniversitatea „Al.I. Cuza” Iaşi, 2008 CONSIDERATIONS ON THE MORPHOLOGY OF THE WEST- PALAEARCTIC PTEROMALIDAE (HYMENOPTERA: CHALCIDOIDEA) MIRCEA-DAN MITROIU “Al. I. Cuza” University Iaşi, Faculty of Biology, Bd. Carol I 20A, 700505 Iaşi, Romania, [email protected] Abstract. The morphology of the head, mesosoma and metasoma of the adult West-Palaearctic pteromalids is reviewed and illustrated. The state of the characters taken into consideration is discussed. The analyzed genera show a mixture of plesiomorphic and apomorphic traits, making difficult to reveal the phyllogenetic relationships within this family. The subfamilies displaying more plesiomorphic characters seem to be Cleonyminae, Asaphinae, Spalangiinae and Diparinae, while the subfamilies Pireninae, Eunotinae, Colotrechninae and Pteromalinae seem to have more apomorphic traits. Key words: Hymenoptera, Chalcidoidea, Pteromalidae, morphology, evolution of characters. Rezumat. Consideraţii asupra morfologiei pteromalidelor vest palearctice (Hymenoptera: Chalcidoidea). Morfologia capului, mezosomei şi metasomei adulţilor de pteromalide vest palearctice este revizuită şi ilustrată. Este discutată starea caracterelor luate în considerare. Genurile analizate prezintă un amestec de trăsături plesiomorfe şi apomorfe, făcând dificilă stabilirea relaţiilor filogenetice din cadrul acestei familii. Subfamiliile cu mai multe caractere plesiomorfe par a fi Cleonyminae, Asaphinae, Spalangiinae şi Diparinae, în timp ce subfamiliile Pireninae, Eunotinae, Colotrechninae şi Pteromalinae par a avea mai multe trăsături apomorfe. Cuvinte cheie: Hymenoptera, Chalcidoidea, Pteromalidae, morfologie, evoluţia caracterelor. Introduction The pteromalids are one of the most diverse groups of parasitic wasps, with more than 600 genera and 4000 species in the world and 200 genera and 1000 species in the West-Palaearctic (Bouček & Rasplus, 1991; Bouček & Heydon, 1997). The morphology of the adult Pteromalidae is presented in the main revisions of the group e.g. Graham (1969), Bouček (1988), Bouček & Rasplus (1991), but the only papers treating this subject in a greater extent are those of Dzhanokmen (1994; 2004; 2007). Bouček (1988a) briefly discussed possible relationships between the pteromalid subfamilies. Cladistic analyses were carried out by Dzhanokmen (2000) and Török & Abraham (2002), but no common agreement on the phylogenetic relationships could be established. Unfortunately, no single character or group of characters proved to be specific for this family, thus most of the authors agree that Pteromalidae is probably a paraphyletic group (Bouček & Heydon, 1997; Török & Abraham, 2002). As it is common for the complex, poorly studied and diverse groups of organisms, the phylogenetic relationships of Pteromalidae are far from being understood. In this context an important task is to identify new characters, including molecular ones, which can be used to reveal the phylogeny of this group. Another important aspect is to establish correctly the synapomorphies and to separate them from the homoplasies (Gibson, 1986). This is not always simple and speculation cannot always be avoided. The aim of this paper is not to perform a cladistic analysis of the group, but to review the morphological characters used in the taxonomy of Pteromalidae, as well as to discuss their possible evolution.

Author: others

Post on 03-Nov-2019

7 views

Category:

Documents


0 download

Embed Size (px)

TRANSCRIPT

  • Lucrările Simpozionului „Entomofagii şi rolul lor în păstrarea echilibrului natural” Universitatea „Al.I. Cuza” Iaşi, 2008

    CONSIDERATIONS ON THE MORPHOLOGY OF THE WEST-

    PALAEARCTIC PTEROMALIDAE (HYMENOPTERA: CHALCIDOIDEA)

    MIRCEA-DAN MITROIU

    “Al. I. Cuza” University Iaşi, Faculty of Biology, Bd. Carol I 20A, 700505 Iaşi, Romania, [email protected]

    Abstract. The morphology of the head, mesosoma and metasoma of the adult West-Palaearctic pteromalids is reviewed and illustrated. The state of the characters taken into consideration is discussed. The analyzed genera show a mixture of plesiomorphic and apomorphic traits, making difficult to reveal the phyllogenetic relationships within this family. The subfamilies displaying more plesiomorphic characters seem to be Cleonyminae, Asaphinae, Spalangiinae and Diparinae, while the subfamilies Pireninae, Eunotinae, Colotrechninae and Pteromalinae seem to have more apomorphic traits. Key words: Hymenoptera, Chalcidoidea, Pteromalidae, morphology, evolution of characters. Rezumat. Consideraţii asupra morfologiei pteromalidelor vest palearctice (Hymenoptera: Chalcidoidea). Morfologia capului, mezosomei şi metasomei adulţilor de pteromalide vest palearctice este revizuită şi ilustrată. Este discutată starea caracterelor luate în considerare. Genurile analizate prezintă un amestec de trăsături plesiomorfe şi apomorfe, făcând dificilă stabilirea relaţiilor filogenetice din cadrul acestei familii. Subfamiliile cu mai multe caractere plesiomorfe par a fi Cleonyminae, Asaphinae, Spalangiinae şi Diparinae, în timp ce subfamiliile Pireninae, Eunotinae, Colotrechninae şi Pteromalinae par a avea mai multe trăsături apomorfe. Cuvinte cheie: Hymenoptera, Chalcidoidea, Pteromalidae, morfologie, evoluţia caracterelor.

    Introduction The pteromalids are one of the most diverse groups of parasitic wasps, with more

    than 600 genera and 4000 species in the world and 200 genera and 1000 species in the West-Palaearctic (Bouček & Rasplus, 1991; Bouček & Heydon, 1997).

    The morphology of the adult Pteromalidae is presented in the main revisions of the group e.g. Graham (1969), Bouček (1988), Bouček & Rasplus (1991), but the only papers treating this subject in a greater extent are those of Dzhanokmen (1994; 2004; 2007). Bouček (1988a) briefly discussed possible relationships between the pteromalid subfamilies. Cladistic analyses were carried out by Dzhanokmen (2000) and Török & Abraham (2002), but no common agreement on the phylogenetic relationships could be established.

    Unfortunately, no single character or group of characters proved to be specific for this family, thus most of the authors agree that Pteromalidae is probably a paraphyletic group (Bouček & Heydon, 1997; Török & Abraham, 2002). As it is common for the complex, poorly studied and diverse groups of organisms, the phylogenetic relationships of Pteromalidae are far from being understood. In this context an important task is to identify new characters, including molecular ones, which can be used to reveal the phylogeny of this group. Another important aspect is to establish correctly the synapomorphies and to separate them from the homoplasies (Gibson, 1986). This is not always simple and speculation cannot always be avoided.

    The aim of this paper is not to perform a cladistic analysis of the group, but to review the morphological characters used in the taxonomy of Pteromalidae, as well as to discuss their possible evolution.

  • Mircea-Dan Mitroiu

    106

    Material and Methods The head capsule, mesosoma and gaster of several West-Palaearctic pteromalid

    genera from the subfamilies Asaphinae, Cleonyminae, Colotrechninae, Diparinae, Eunotinae, Herbertiinae, Miscogasterinae, Ormocerinae, Pireninae, Pteromalinae and Spalangiinae were analyzed using optical and electronic microscopy. The classification follows Bouček (1988). The articulated appendages were not included in this study, but will be treated in a further paper.

    Results and Discussion Head (Figs. 1-3, 8-34, 60, 62, 63). In most pteromalids the position of the head is orthognathous, its main axis being perpendicular on the longitudinal axis of the body. In this case, the mandibles are oriented downwards and the occipital foramen is situated at about the middle point between the vertex and the mandible insertion. Two exceptions are the members of the subfamilies Spalanginae and Cerocephalinae, where the head is almost prognathous, the mandibles being oriented forward and the occipital foramen being situated closer to the vertex than the mandibles insertion (Fig. 25). This character could be regarded as a plesiomorphy because the primitive apocritans have a rather prognathous head. Dzhanokemen (1994) instead considers the prognathous head to be secondary (reversion) in pteromalids, a specialization related to host location in narrow places. The general shape of the head is very diverse. Some genera have a round head in frontal view, its width being approximately equal to its height as in Pteromalus Swederus (Pteromalinae) (Fig. 10), Notanisus Walker (Cleonyminae) (Fig. 11) or Systasis Walker (Ormocerinae) (Fig. 12). In some species the height can be greater than the width, the head being strongly elongated as in Spalangia Latreille (Spalangiinae) (Fig. 9); sometimes the height is smaller than the width as in Herbertia Howard (Herbertiinae) (Fig. 13) or Sphegigaster Spinola (Pteromalinae) (Fig. 21). In Asaphes Walker (Asaphinae) (Fig. 8) and Eunotus Walker (Eunotinae) (Fig. 17) the head is approximately triangular. Dorsally the head can be either thin (short) as in Spintherus Thomson (Pteromalinae) or very massive (broad) as in Cratomus Dalman (Cratominae).

    The antennal insertion (torulus, toruli) can vary from being placed at about the same distance from the anterior ocellus and the lower clypeal margin as in Systasis (Fig. 12) and Colotrechnus Thomson (Colotrechninae) (Fig. 19) or closer either to the median ocellus as in Panstenon Walker (Panstenoninae) and Dipara Walker (Diparinae) (Fig. 18), or to the clypeal margin as in Asaphes (Fig. 8), Herbertia (Fig. 13), Macroglenes Westwood (Pireninae) (Figs. 14, 15) and Eunotus (Fig. 17). An extreme case is found in Spalangia (Fig. 9) where the toruli are situated just above the oral fosa. The inferior position of the toruli can be regarded as a plesiomorphy and their higher position as an apomorphy since the first case characterizes the most primitive groups of apocritans.

    The frons can have two more or less deep furrows (scrobes) where the antennal scape can lay. Sometimes, in the centre of the frons, an interantennal crest may be present, especially in the parasitoids which develop in xylophagous coleopterans as in Cerocephala Westwood (Cerocephalinae), perhaps as an antennal protection when the females enter the dirty galleries in wood. The face can be almost flat or more or less protruding at the level of toruli as in Coelopisthia Förster (Pteromalinae). The temples can be very large as in Conomorium Masi (Fig. 60) (Pteromalinae) or very small, almost indistinct, as in Peridesmia. The genae are usually flat, but there are not rare the cases when a depression exists just above the mandible insertion as in Catolaccus Thomson

  • Consideration on the morphology of the west-palearctic Pteromalidae (…)

    107

    (Pteromalinae) or Sphegigaster (Fig. 23). This may allow a wider opening of the mandibles and it is regarded as an apomorphy (Dzhanokmen, 1994).

    Figures 1-7. General morphology of Pteromalidae: 1. Pteromalus elevatus (Walker), female, head

    in frontal view; 2. Idem, head in posterior view; 3. Idem, head in dorsal view; 4. Idem, mesosoma in dorsal view; 5. Idem, mesosoma in lateral view; 6. Halticoptera andriescui Mitroiu, detail of

    posterior part of scutellum, metanotum and propodeum; 7. P. elevatus, female, metasoma in lateral view (ao = anterior ocellus; ax = axilla; axi = axillula; bf = basal fovea; ca = callus; ce = compound eye; cl = clypeus; c1-c3 = coxae 1-3; do = dorsellum; el = eye length; fa = face; far = frenal area; fl

    = frenal line; fm = foramen magnum; fr = frons; ge = gena; hca = hypostomal carina; hp = hypopygium; hy = hypostome; ltb = lower tentorial bridge; ma = mandibles; mar = median area; mc

    = median carina; mes = mesosternum; met = metanotum; mlc = maxillo-labial complex; mp = mesepimeron; mpl = metapleura; ms = malar sulcus; msp = mesepisternum; mspa = malar space; nu

    = nucha; occ = occiput; of = oral fosa; OOL = oculo-ocellar line; ovi = ovipositor; pc = pronotal colar; pe = petiole; pge = postegena; pl = plica; pn = pronotal neck; po = posterior ocellus; pocc =

    postocciput; POL = postocellar line; pr = propleura; pre = prepectus; pro = propodeum; sc = scutellum; sp = spiraculum; sps = spiracular sulcus; te = temple; teg = tegula; tel = temple length; to

    = torulus; t1-t7 = gastral tergites 1-7; utb = upper tentorial bridge).

  • Mircea-Dan Mitroiu

    108

    The clypeal margin can be straight, not very large, as in Notanisus (Fig. 11) or unusually wide as in Habritys Thomson (Pteromalinae), convex (protruding downwards) as in Macroglenes (Figs. 14, 15), more or less concave (emarginated) as in Dipara (Fig. 18) or with 1-3 teeth that can be symmetrical or not. The first case can be found in Stenomalina Ghesquière or Cyrtogaster Walker (Pteromalinae), both with 3 symmetrical teeth, the middle one being the largest. Two symmetrical teeth can be found ,for example, in Sphegigaster (Fig. 23). A single median tooth is found in Trigonoderini (Pteromalinae), such as Trigonoderus Westwood. The second situation is present in many genera of Miscogasterinae e.g. Miscogaster Walker where on the left side there are 2 unequal teeth and on the right side only one tooth (Fig. 22); the two teeth from one side can be fused, as in the case of Halticoptera Spinola (Miscogasterinae). In Rohatina monstrosa Bouček (Pteromalinae) two strong projections can be found near the mouth corners, between the clypeus and the malar sulcus. Dzhanokmen (1994) considers the emarginated clypeal margin as the plesiomorphic state in pteromalids, arguing that this “is the most typical in the most generalized subfamily Pteromalidae” (p. 114). However, the plesiomorphic state of Pteromalinae needs confirmation. The compound eyes occupy most of the lateral sides of the head. Their general shape is ovoid, with their height larger than their width and their inner margins straight or slightly diverging ventrally. In some genera (e.g. Habritys) the eyes are small, while in others they are very large (e.g. the males of some Macroglenes (Fig. 14), where the upper part of the eye consists in larger ommatidiae). Most of the time the eyes are glabrous, but sometimes they may be covered by a more or less dense pilosity as in Spalangia (Fig. 9) or Herbertia (Fig. 13). The ocelli are always present: a median one and two lateral. They are located on the vertex, on a triangular protuberance (stemmaticum). The distance between one posterior ocellus and the adjacent eye margin is called the ocello-ocular line (OOL), and the distance between the two posterior ocelli is called the post-ocellar line (POL). The dimensions of the ocelli may vary, but usually they have the same size. An exception is the median ocellus of some Macroglenes males, which can be very large (Fig. 14). According to Bouček (1988), the posterior part of the head may reveal some important characters for the taxonomy of the group. Most of the pteromalids lack an occipital carina. This is present however in a few genera such as Spalangia (Fig. 25) and Asaphes, in the latter the occipital carina being accompanied by the primary occipital suture (Fig. 24). The presence of the occipital carina and the primary occipital suture is regarded as apomorphic (secondary development) by Dzhanokmen (1994), but this may be considered as retention of the primitive state in Apocrita, similarly with the prognathous position of the head. Two hypostomal carinae are found on the both sides of the oral fosa, continuing more or less dorsally towards the foramen magnum. The portion between the foramen magnum and the oral fosa is usually closed in pteromalids by the lower tentorial bridge (Fig. 2). This can be either totally (in Macromesus Walker (Macromesinae), according to Dzhanokmen (1994)), or partially replaced by the postgenal bridge (in Notanisus (Fig. 27)) and/or the hypostomal bridge (in Dipara (Fig. 32)). The upper tentorial bridge is found on the ventral side of the foramen magnum (Fig 2). Dzhanokemen (1994) states that the presence of the lower tentorial bridge must be considered as plesiomorphic since it characterize most of the species of Pteromalinae, which she considers to be less advanced; thus the presence of the postgenal bridge and the

  • Consideration on the morphology of the west-palearctic Pteromalidae (…)

    109

    hypostomal bridge would be secondary. This may be right if we analyze the situation found in Chalcididae, where the latter structures are absent.

    Figures 8-15. Pteromalid head capsule in frontal view: 8. Asaphes suspensus (Nees), female; 9.

    Spalangia fuscipes Nees, male; 10. Pteromalus elevatus (Walker), female; 11. Notanisus versicolor Walker, male; 12. Systasis encyrtoides Walker, female; 13. Herbertia wallacei Burks, female; 14.

    Macroglenes decipiens (Graham), male; 15. M. decipiens, female (not to the same scale).

  • Mircea-Dan Mitroiu

    110

    Figures 16-23. Pteromalid head capsule in frontal view: 16. Halticoptera andriescui Mitroiu, male; 17. Eunotus cretaceus Walker, female; 18. Dipara petiolata Walker, male; 19. Colotrechnus viridis

    (Masi), female; 20. Miscogaster hortensis Walker, female; 21. Sphegigaster nigricornis (Nees), female; 22. M. hortensis, detail of the clypeus; 23. S. nigricornis, detail of the clypeus (not to the

    same scale).

  • Consideration on the morphology of the west-palearctic Pteromalidae (…)

    111

    Figures 24-31. Pteromalid head capsule in posterior view: 24. A. suspensus, female; 25. S. fuscipes, male; 26. P. elevatus, female; 27. N. versicolor, male; 28. S. encyrtoides, female; 29. H. wallacei, female; 30. M. decipiens, female; 31. E. cretaceus, male (pgb = postgenal bridge; pos = primary

    occipital suture; oc = occipital carina) (not to the same scale).

  • Mircea-Dan Mitroiu

    112

    But, if we consider the Leucospidae (another primitive group of chalcids), the situation is exactly opposite, the lower tentorial bridge being absent and the postgenal and the hypostomal bridges being present (Dzhanokmen, 1994). This seems to be the situation in Notanisus (Cleonymidae), where the space between the foramen magnum and the oral fosa is partly closed by the postgenal bridge. This observation supports Bouček’s assertion that the Cleonyminae is one of the most primitive groups of Pteromalidae (Bouček, 1988a).

    Mesosoma (Figs. 4-6, 35-47). In the aprocritan hymenopterans the mesosoma includes the prothorax, the mesothorax, the metathorax and the propodeum (the first abdominal segment fused to the thorax). The prothorax consists mainly in its dorsal sclerite – the pronotum, which can be rarely rather long and narrow, as in Spalangia (Fig. 36), Notanisus (Fig. 38) or Panstenon, and usually shorter and wider (Figs. 35, 39-43, 45-47), sometimes almost as wide as the mesoscutum, as in Norbanus Walker (Pteromalinae) or Herbertia (Fig. 40). The long pronotum can be regarded as the plesiomorphic state for pteromalids and the short one as apomorphic because in the more primitive groups of chalcids the pronotum tends to be rather well developed. In rare cases the pronotum can be wider in its anterior part than its posterior part, as in Spathopus Ashmead (Pireninae). The pronotum can make a distinct angle and form a neck and a collar, as in Pteromalus Swederus (Pteromalinae) (Fig. 5) and Sphegigaster (Fig. 43), or it can be more or less rounded, without forming a distinct collar, as in Seladerma Walker (Miscogasterinae), Notanisus (Fig. 38), Miscogaster, or Spintherus. In its anterior part, the collar can have a sharp, raised margin as in Merismus Walker (Miscogasterinae), Cyrtogaster Walker or Chlorocytus Graham (Pteomalinae), or some more or less rounded teeth as in some Sphegigaster. In some cases e.g. Syntomopus Walker (Pteromalinae), the pronotum is almost rectangular. The mesothorax. The mesoscutum has three lobes, a median lobe and two lateral ones, the latter also called scapulae (Fig. 39). In Asaphinae (Fig. 35), Spalangiinae (Fig. 36), Ormocerinae (Fig. 39), Herbertiinae (Fig. 40), Pireninae (Fig. 41), Eunotinae (Fig. 43), Diparinae (Fig. 44) and most Miscogasterinae (Fig. 46) the lateral lobes are clearly delimited from the median one by the complete notauli. In other cases e.g. most Pteromalinae (Fig. 37, 47) the notauli are incomplete, sometimes present only in the anterior part of the mesoscutum, thus not reaching its hind margin. Because some of the most primitive chalcids have complete notauli, this may be considered as the plesiomorphic state in Pteromalidae. The scutellum is situated posterior to the mesoscutum. The axillae and the axillulae are situated on the lateral sides of the scutellum (Fig. 4). The scutellum is usually more or less convex but there are genera where it is virtually flat, being in the same plan as the mesoscutum. In these cases the mesosoma is flattened, as in Rakosina Bouček or Psilonotus Walker (Pteromalinae). In Colotrechnus (Fig. 45) the axillulae are larger than usual and the axillae are more advanced towards the mesoscutum. At the posterior end of the scutellum lays the frenal area which is usually separated from the rest of the scutellum by the frenal line (Fig. 6). Sometimes e.g. in Platneptis Bouček (Pteromalinae) the frenal line is virtually indistinct. In some cases the sculpture of the frenal area is distinct from the rest of the scutellum, as in Lamprotatus Westwood (Miscogasterinae) where it has some longitudinal crests, or in Eunotus (Fig. 43) where the frenal area has larger reticulation than the rest of the scutellum. The lateral margins of the scutellum can converge more or less in the anterior part, in some cases virtually fusing as in some Halticoptera (Fig. 42). Most of the times there are no special

  • Consideration on the morphology of the west-palearctic Pteromalidae (…)

    113

    marks on the scutellum except the reticulation, but in Notoglyptus Masi (Pteromalinae) there is a conspicuous central fovea. Another exceptional case is Scutellista Motschulsky (Eunotinae) where the scutellum is far exerted backwards, covering the propodeum and part of the gaster (Fig. 61).

    Figures 32-34. Pteromalid head capsule in posterior view: 32. D. petiolata, male; 33. C. viridis,

    female; 34. M. hortensis, male. Figures 35-40. Pteromalid mesosoma in dorsal view: 35. A. suspensus, female; 36. S. fuscipes, male; 37. P. elevatus, female; 38. N. versicolor, male; 39. S. encyrtoides, female; 40. H. wallacei, female (hyb = hypostomal bridge; ml = middle lobe; no =

    notaulus; sc = scapula or lateral lobe) (not to the same scale).

  • Mircea-Dan Mitroiu

    114

    Figures 41-49. Pteromalid mesosoma in dorsal view: 41. M. decipiens, female; 42. H. andriescui,

    male; 43. E. cretaceus, female; 44. D. petiolata, male; 45. C. viridis, female; 46. M. hortensis, female; 47. S. nigricornis, female. Figures 48-49. Petiole and first gastral tergites in dorsal view:

    48. A. suspensus, female; 49. S. fuscipes, male (not to the same scale).

  • Consideration on the morphology of the west-palearctic Pteromalidae (…)

    115

    The mesopleurae are large and divided in two areas by the pleural line (femoral groove): an anterior area called mesepisternum and a posterior area called mesepimeron, the latter having an upper and lower part (Fig. 5). Usually the mesopleura is only partly reticulated but sometimes all its surface is sculptured, as in some species of Mesoplobus Westwood (Pteromalinae). As in all chalcids a small sclerite called prepectus can be found between the pronotum and the mesepistenum (Fig. 5). In some cases it is very small, shorter than the tegula as in Norbanus, but usually it is well developed and approximately triangular. The prepectus can be smooth as in Pteromalus, Plutothrix Förster (Pteromalinae) or Merismus Walker, or reticulated as in Chlorocytus, Miscogaster or Trigonoderus, with an anterior carina as in Merismus or without as in Miscogaster.

    The metathorax is compressed between the mesothorax and the propodeum (Figs. 4-6). The dorsellum can be smooth or with different reticulation, glabrous or with a few setae. Metapleura is divided by the metapleuran groove in metepisternum and metepimeron.

    The propodeum (usually compared with the scutellum length) varies from being rather long as in Asaphes (Fig. 35), Notanisus (Fig. 38), Dipara (Fig. 44) or Panstenon, short as in Systasis (Fig. 39), Herbertia (Fig. 40), Macroglenes (Fig. 41) or Eunotus (Fig. 43), or extremely short as in Colotrechnus (Fig. 45). The longer propodeum can be considered as the plesiomorphic state and the reduced one as the apomorphic state. The propodeum can be smooth as in Macroglenes (Fig. 41), uniformly sculptured as in Sphaegigaster (Fig. 47) or with a central (median) area with different reticulation. This may include a more or less regular median (longitudinal) carina as in Spalangia (Fig. 36), Halticoptera (Fig. 42) or Dipara (Fig. 44) and/or a costula (transversal carina) as in some Pteromalus or Eunotus (Fig. 43). Laterally, the median propodeal area may be margined by plicae, which can vary from being well developed, reaching the metanotum as in Miscogaster (Fig. 46), to incomplete as in some Halticoptera (Fig. 6). In its anterior part, at variable distance from the metanotum there are the two respiratory spiracles. The angle between the propodeum and the rest of the mesosoma can differ, the propodeum being from almost horizontal as in Psilonotus to almost vertical, as in Catolaccus. The posterior part of the propodeum can be short as in Macroglenes (Fig. 41), Colotrechnus (Fig. 45), or more or less exerted towards the gaster, in the latter case forming the so called nucha (Fig. 6) as in Herbertia (Fig. 40). Metasoma (Figs. 7, 48-59). As in all the apocritans, the true abdomen consists in the propodeum (analyzed above) together with the petiole and the rest of the posterior segments, the latter forming the gaster. The petiole and the gaster form the metasoma. The development and the shape of the petiole vary considerably. It can be from extremely small, virtually invisible dorsally in which case the gaster is called sessile (the Pireninae (Fig. 52), Eunotinae (Fig. 55), Colotrechninae (Fig. 57) or most of the Pteromalinae (Fig. 50)) to long and narrow as in Spalangia (Fig. 49), Dipara (Fig. 56) or Sphegigaster (Fig. 59), the gaster being called petiolate. An intermediate situation is the virtually quadrate petiole found in Asaphes (Fig. 48) or the conical one found in some Notanisus (Fig. 51). A special situation is found in Callitula Spinola (Pteromalinae) where the petiole appears to have three parts: a central one representing the true petiole and two lateral ones, which are in fact extensions of the first gastral tergite. The petiole can be almost smooth or with different types of sculpture, as in Asaphes (Fig. 48), Spalangia (Fig. 49), Halticoptera (Fig. 54) or Sphegigaster (Fig. 59). Bouček (1988) and Dzhanokmen (2007) consider the short petiole as plesiomorphic, the latter author arguing that this is the most common

  • Mircea-Dan Mitroiu

    116

    situation encountered in the Pteromalinae. The long petiole would be in this case a secondary formation. Another possibility is that the developed petiole is retained from the primitive apocritans.

    Figures 50-58. Petiole and first gastral tergites in dorsal view: 50. P. elevatus, female; 51. N.

    versicolor, male; 52. M. decipiens, female; 53. H. wallacei, female; 54. H. andriescui, male; 55. E. cretaceus, female, whole metasoma; 56. D. petiolata, male; 57. C. viridis, female; 58. S.

    encyrtoides, female (not to the same scale).

  • Consideration on the morphology of the west-palearctic Pteromalidae (…)

    117

    Figures 59-63: 59. Sphegigaster nigricornis, female, petiole in dorsal view; 60. Conomorium amplum (Walker), female, head and anterior part of mesosoma in dorsal view; 61. Scutellista

    obscura (Förster), female in lateral view; 62. Leptomeraporus nicaee (Walker), male, head in lateral view; 63. idem, head in frontal view (sc = scutellum) (not to the same scale).

  • Mircea-Dan Mitroiu

    118

    Regarding the structure of the gaster, there are seven segments posterior to the petiole, but sometimes not all of them are visible. The last one is in fact formed by the merging of four different segments. On the sixth tergite the only functional pair of gastral spiracles is situated and the last tergite (epipygium) bears the pygostili, which can have equal (most of the species) or unequal setae (e.g. some Halticoptera). The hipopygium (the end of the last visible abdominal sternite (Fig. 7)) can be situated closer to or more remote from the tip of the gaster. The gaster can vary in dimension when compared with the length of the head and thorax. In most cases it is longer than broad, an extreme case being that of Eulonchetron Graham or Gastracanthus Westwood (Pteromalidae) where the gaster is unusually long and narrow. At the opposite end is the very short, ovate gaster, which sometimes can be even wider than long, as in Tomicobia Ashmead, Coelopisthia, Tritneptis Girault (Pteromalinae) or Eunotus (Fig. 55). Dzhanokmen (2007) states that the elongated oval-rectangular and moderately laterally compressed metasoma is the plesiomorphic state in pteromalids. The gastral tergites can have various degrees of development. They can be about of the same length, but usually the first tergite is slightly to distinctly longer than the others. The extreme cases are those when the first tergite is very large and convex, covering most or virtually all of the remaining segments, as in Herbertia (Fig. 53), Eunotus (Fig. 55), Dipara (Fig. 56) or Sphegigaster. The hind margin of the first tergite can be straight or slightly convex (most of the species), with 1-3 lobes (some Norbanus, Colotrechnus (Fig. 57)), medially incised (Miscogaster, some Halticoptera), or deeply emarginated (Cyrtogaster Walker). Dorsally the tergites can be either convex, strongly sclerotized as in Eunotus, Herbertia or Sphegigaster, or less so as in Macroglenes (Fig. 52) or Systasis (Fig. 58). According to Dzhanokmen (2007) the approximately equal gastral tergites are the plesiomorphic state in pteromalids. Body sculpture. The body sculpture of pteromalids is quite diverse. According to Bouček & Rasplus (1991), it can be classified in several types: piliferous puncturation, reticulation and rugulosity, which usually appear in different combinations. The piliferous puncturation is relatively rare in pteromalids and consists in circular punctures bearing hairs. It can be found in Roptrocerus Ratzeburg (Pteromalinae), Spalangia (Fig. 9) or Systasis (Fig. 39) where the more or less deep punctures are separated by smooth, reticulated or rugulose interspaces. Apart from the usual punctures that may occur on the head, two deeper punctures called tentorial pits may be present in the clypeal region in Janssoniella Kerrich (Pteromalinae), Systasis (Fig. 12) and a few other genera. The reticulation is the most common and consists in a network of alveoli. It can be of two different types: engraved and raised. In the engraved reticulation the alveoli are separated by very fine lines, which are not raised above the body surface, this appearing virtually smooth as in Macroglenes (Fig. 41) or very finely reticulate, as in Dipara (Fig. 18) or Miscogaster (Figs. 20, 22). The engraved reticulation together with the piliferous punctures characterizes for example the mesoscutum of Semiotellus Westwood (Ormocerinae). In the raised reticulation the alveoli are separated by fine walls which are clearly raised above the body surface. This is the most common type of sculpture in pteromalids, covering the head and mesosoma of most of the species (Figs. 1, 3, 4, 11, 16, 17, 21, 42-44, 47). However it can present many variations. The usually polygonal alveoli can have different sizes and when they are small the body appears mate.

  • Consideration on the morphology of the west-palearctic Pteromalidae (…)

    119

    The rugulose sculpture is usually regular, appearing as striations or wrinkles located in different places of the body. It is usually encountered on the lower part of the face is many genera of pteromalids such as Sphegigaster (Fig. 23), but sometimes it can be spread beyond the level of the toruli, as in Hobbya Delucchi (Pteromalinae). The males of some species may have specific sinuous lines among the reticulation of their face, frons and temples, as in Meraporus Walker, Leptomeraporus Graham (Figs. 62, 63) or Peridesmia Förster (Pteromalinae). These lines appear smooth and dark compared with the surrounding areas and probably represent species identity marks for the females. Conclusions The pteromalids are a morphologically very diverse group of parasitoids, if only considering the West-Palaearctic fauna. The analyzed genera show a mixture of plesiomorphic and apomorphic traits, making difficult to reveal the phyllogenetic relationships within this family. The main problem is establishing the synapomorphies; it can be difficult sometimes to decide whether a certain character is plesiomorphic or apomorphic, especially when reversions may be involved. The subfamilies displaying more plesiomorphic characters seem to be Cleonyminae, Asaphinae, Spalangiinae and Diparinae, while the subfamilies Pireninae, Eunotinae, Colotrechninae and Pteromalinae seem to have more apomorphic traits. This confirms Bouček’s statement (Bouček, 1988a) that Cleonyminae is probably one of the basal groups of pteromalids connecting it to the eupelmids, and disagrees with Dzhanokmen (Dzhanokmen, 2000), who considers the Pteromalinae as one of the most generalized groups of pteromalids. However, until monophyletic groups are established it is premature to make any considerations on the phyllogenetic relationships within ‘Pteromalidae’. Acknowledgements I am indebted to Dumitru Răileanu, “Al. I. Cuza” University Iaşi, for preparing the specimens for electomicroscopy. References Bouček, Z., 1988a. Australasian Chalcidoidea (Hymenoptera). A biosystematic revision of genera of fourteen

    families, with a reclassification of species. CAB International, Wallingford, Oxon, U.K., Cambrian News Ltd.

    Bouček, Z. 1988a. An overview of the higher classification of the Chalcidoidea (parasitic Hymenoptera). Advances in Parasitic Hymenoptera Research: Proceedings of the Second Conference on Taxonomy and Biology of Parasitic Hymenoptera, Gainesville, November, 1987: 11-23.

    Bouček, Z., Heydon, L. S., 1997. Family Pteromalidae. In Gibson, P. A. G., Huber, T. J., Wooley, B., J. (Eds.). Annotated Key to the Genera of Nearctic Chalcidoidea (Hymenoptera). NRC-CNRC Res. Press, Otawa, Canada.

    Bouček, Z., Rasplus, J. Y., 1991. Illustrated key to West-Palearctic genera of Pteromalidae (Hymenoptera, Chalcidoidea). Techniques et Pratiques, INRA, Paris.

    Dzhanokmen, K. A., 1994. Comparative morphology of pteromalid head capsule (Hymenoptera, Chalcidoidea, Pteromalidae). Russian Entomological Journal, 3 (1-2): 109-121.

    Dzhanokmen, K. A., 2004. Some aspects of the pteromalid mesosoma morphology (Hymenoptera: Chalcidoidea, Pteromalidae). Proceedings of the Russian Entomological Society, 75 (1): 168-179.

    Dzhanokmen, K. A., 2000. Phylogenetic Relations in Palaearctic Subfamilies of Pteromalidae (Hymenoptera, Chalcidoidea). Zoologicheskiy Zhurnal, 80 (2): 232-240.

    Dzhanokmen, K. A., 2007. A Brief Description of the Metasoma in Pteromalids (Hymenoptera, Chalcidoidea, Pteromalidae). Entomological Review, 87 (1): 66-72.

    Gibson, G. A. P. 1986. Evidence for monophyly and relationships of Chalcidoidea, Mymaridae and Mymarommatidae (Hymenoptera: Terebrantes). Canadian Entomologist 118 (3): 205-240.

  • Mircea-Dan Mitroiu

    120

    Graham, M. W. R. de V. 1969. The Pteromalidae of north-western Europe (Hymenoptera: Chalcidoidea). Bulletin of the British Museum (Natural History) (Entomology) Supplement 16: 1-908.

    Török, M., Abraham, R. 2002. Sampling ground or truly monophyletic? Cladistic analyses applied to the phylogeny of Pteromalidae (Hymenoptera: Chalcidoidea). In Melika, G., Thuróczy, C. (Eds.). Parasitic wasps: evolution, systematics, biodiversity and biological control. Agroinform Kiadó & Nyomda KFT, Budapest, Hungary.